I. Field
The ideas presented herein relate to the field of data communications. More specifically, to a method and apparatus for determining network latency for delivery of packet-based information.
II. Description of the Related Art
The use of wireless communication systems are well known for transmitting information between, for example, fixed stations and one or more geographically dispersed mobile receivers. For example, satellite and/or terrestrial wireless communication systems have been used in the trucking industry for many years to provide messaging and location information between fleet-owned dispatch centers and their respective tractor-trailer vehicles. Such systems offer significant benefits to fleet owners because they allow almost instantaneous communications and real-time position information. In addition, many such systems provide remote monitoring of the performance characteristics of each fleet-owned vehicle, such as the average vehicle speed, RPM, idle time, and other characteristics.
In such wireless communication systems, fleet-owned dispatch centers typically communicate with their respective vehicles through a central station, otherwise known as a hub, network management center (NMC), or network management facility (NMF). Communications between dispatch centers and the central station are often sent over land-based communication systems such as telephone or fiber-optic networks. The central station then forwards information to one or more vehicles via a satellite or terrestrial communication system.
Each vehicle in the communication system is equipped with a transceiver, otherwise known as a mobile communication terminal (MCT), for communicating message and location information to their respective dispatch centers via the satellite or terrestrial communication system and central station. The MCT typically also comprises an interface device which displays text messages to one or more vehicle occupants and accepts either voice or text messages to be transmitted to the vehicle""s fleet-owned dispatch center. Furthermore, the MCT may further comprise circuitry which allows it to communicate with one or more Electronic Control Units (ECUs) located at various points throughout the vehicle. Each ECU provides information relating to the operational performance of the vehicle to the digital computer indicating characteristics including, but not limited to, vehicle speed, engine RPM, and miles traveled.
The wireless communication system described above allows vehicle occupants to easily contact their respective dispatch centers in order to keep fleet personnel apprised of various events throughout a typical delivery cycle. For example, upon arrival at a predetermined pickup destination, a truck driver may contact a dispatch center associated with the vehicle to alert fleet personnel of the time and location of the arrival. Similarly, after the truck has been loaded at the pickup destination, the driver may send a message to the dispatch center indicating the time of departure, the location from where the departure occurred, and a description of the goods that is being transported. Another example where a vehicle operator might transmit a status message to the dispatch center is when an unscheduled stop has been made and/or when the vehicle departs from the unscheduled stop.
In many instances, fleet owners need to communicate with hundreds, and sometimes thousands, of vehicles each day. It is also often important that messages be delivered in a timely fashion. Occasionally, delays may be caused by disruptions of the satellite or terrestrial communication system. When this occurs, messages may be delayed by seconds, or as much as hours or days. Obviously, if significant delays occur, it could have a dramatic effect on fleet efficiency as well as increase costs for fleet owners. Therefore, there is a need for network operators to be able to detect delays in the communication network(s), so that problems with those networks can be identified and fixed.
A method and apparatus for detecting communication network delays. In one embodiment, an apparatus comprises a receiver for receiving a message from a vehicle, said message comprising a time stamp indicating when the message was transmitted. A processor is used for determining a time that the message was received, for determining a time difference between the time stamp and the time when the message was received, for comparing the time difference to a predetermined time, for determining a number of messages received having a time difference greater than said predetermined time, and for generating a notification if said number of messages received having a time difference greater than said predetermined time exceeds a predetermined number. Finally, an interface is used for providing the notification to an entity.
In another embodiment, an apparatus for detecting communication network delays comprises a signal-bearing medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform a method for validating a vehicle operator, the method comprising operations of receiving a message from a vehicle, the message comprising a time stamp indicating when the message was transmitted, determining a time that the message was received, determining a time difference between the time stamp and the time when the message was received, comparing the time difference to a predetermined time, determining a number of messages received having a time difference greater than said predetermined time, and generating a notification if said number of messages received having a time difference greater than said predetermined time exceeds a predetermined number.
In yet another embodiment, a method for detecting communication network delays comprises receiving a message from a vehicle, said message comprising a time stamp indicating when the message was transmitted, determining a time that the message was received, determining a time difference between the time stamp and the time when the message was received, comparing the time difference to a predetermined time, determining a number of messages received having a time difference greater than said predetermined time, and generating a notification if said number of messages received having a time difference greater than said predetermined time exceeds a predetermined number.